In general, image transfer materials are known in the art. For example, U.S. Pat. No. 5,501,902 to Kronzer describes an ink jet printable heat transfer material comprised of a first layer of film, paper, web or foil, and a second, ink receptive layer, having a melting point of 65° C. to 180° C. composed of particles of thermoplastic polymer having a certain dimension, a film forming binder based on the weight of the thermoplastic polymer, and a cationic polymer.
Similarly, U.S. Pat. No. 5,798,179 to Kronzer is directed to a heat transfer material having cold release properties for use in ink jet printing made of three layers. The first layer is a film or cellulosic nonwoven web. The second layer is composed of a thermoplastic polymer having essentially no tack at the transfer temperature, such as hard acrylic polymer or poly(vinyl acetate), and having various other characteristics. The third layer includes a thermoplastic polymer which melts between 65° C. and 180° C.
The present invention is an improvement over these patents and other heat transfer recording materials and sheets, in general. Ink jet printers utilize inks that are mostly water-based. When printing images on heat transfer recording sheets, it is important to eliminate the ink solvent, which is comprised primarily of water, because the printed image must be dry before it can be effectively transferred. This is either accomplished by waiting a long period of time for the water to evaporate, or, to remove the water in another manner.
In the recording sheets of the present invention, which comprise an ink receiving layer made of microporous polymeric film, the microporous polymeric film functions as a reservoir and an evaporator for the water. After the image is printed, the micropores of the film absorb the ink solvent by capillary action, removing it from the surface of the layer. The ink solvent is thereafter quickly evaporated into the air through the micropores. This allows for the recording sheet to dry very quickly, which, in turn, results in virtually no waiting time for ink drying after printing and less image smearing problems.
Accordingly, it is the broad object of the present invention to provide an improved heat transfer recording sheet, which can be printed with personalized designs that are transferred onto target substrates such as paper, textiles, metal and ceramics.
It is another object of the present invention to provide a method to transfer a printed image to a target substrate.